Colossal-magnetoresistance materials: manganites and conventional ferromagnetic semiconductors

Experimental data and their theoretical interpretation are presented for th e colossal magnetoresistance (CMR) materials to which conventional ferromag netic semiconductors and manganites belong. The similarity between the tran sport and magnetotransport properties of the ferromagnetic semiconductors a nd manganites is stressed. Different theoretical points of view on the phys ics of the phenomenon are presented, including the magnetoimpurity theory a nd "magnetization + Jahn-Teller phonon" theory. Of the manganites, the La-b ased underdoped, normally doped, and overdoped manganites are discussed in detail, including the dilemma "canted antiferromagnetic ordering or phase s eparation" and different models of charge ordering. Radical difference betw een the Pr-based and La-based manganites is explained. Layered manganites a re considered, too. (C) 2001 Elsevier Science B.V. All rights reserved.